FORAMEN OVALE. 537 



has remained open ; because in several persons in whom it was found by 

 dissection to have remained open, there were no appearances during life, 

 that indicated the presence of disoxygenaied blood in the aortic system. It 

 is probable, that the small size of the foramen ovale, the valvular structure 

 which generally exists there, and the complete occupation of the left auricle 

 by the blood flowing from the pulmonary veins, prevent the passage of blood 

 from the right auricle to the left, in such persons ; whereas in the case in 

 question, the opening between the auricles was very large indeed, and there 

 was no appearance of a valve about it. 



Although it be admitted, that in adults with the foramen ovale pervious, there 

 is no transmission of blood from the right to the left auricle ; there is every 

 reason to believe, that this transmission goes on steadily in the foetus. To 

 the arguments derived from the structure and the nature of the case, it may 

 be added, that the pulmonary veins, in the foetal state, carry to the left auri- 

 cle a quantity of blood, not sufficient to fill it ; while the vense cavae carry to 

 the right auricle, not only the whole blood of the body, but of the umbilical 

 cord and placenta : some of which must flow into the unfilled left auricle, 

 when the right auricle becomes fully distended. 



The question, how far the functions of the heart and lungs are dependent upon 

 the brain, is very important, and has often been agitated with great zeal. In 

 favor of the opinion that the motions of the heart are independent of the 

 brain, may be stated the numerous cases in which the brain has been deficient 

 in children, who have notwithstanding lived the full period of utero-gesta- 

 tion, and even a short time after birth, and have arrived at their full size, 

 with every appearance of perfect vigor and action in the heart. In support 

 of the doctrine, that the action of the heart is immediately dependent upon 

 the brain, it may be observed, that no organ of the body appears to be so 

 much influenced by passions and other mental affections as the heart. These 

 contradictory facts have occasioned this question to be considered as unde- 

 cided, if not incapable of solution ; although Cruikshank and Bichat* have 

 stated circumstances very favorable to the opinion that the motions of the 

 heart are independent of the brain. 



This question seems now to be settled by the experiments of Dr. Legallois, a 

 physician of Paris, which prove, that in animals who have suffered decapi- 

 tation, the action of the heart does not cease as an immediate consequence 

 of the removal of the head ; but its cessation is an indirect effect, induced by 

 suspension of respiration. That respiration is immediately affected by 

 decapitation, and depends upon the influence of the brain transmitted 

 through the eighth pair of nerves. That the action of the heart will con- 

 tinue a long time after decapitation, if inflation of the lungs, or artificial 

 respiration, be performed; but, on the contrary, if the spinal marrow be de- 

 stroyed, the action of the heart ceases irrecoverably. 



The inference from these experiments seems very conclusive, that the Spinal 

 marrow, and not the brain, is the source of the motions of the heart. 



* See Cruikshank's Experiments on the Nerves and Spinal marrow of living Animals ; 

 London Philosophical Transactions for 1795. The eighth experiment has a particular relation 

 to this subject. Bichat's researches, part 2, article 9. 



The Abbe Fontana has considered this subject in his Treatise on the Venom of the Viper, 

 vol. ii. page 194, English translation ; and also in some of his other works. 



